District of



April 26' 1927. H. F. LOWENSJTEIN ET AL Re. 0

RADI O RECEIVING APPARATUS originalriled Aug. 14, 1922 B o/a JIVIV'CIJOIYIZP noe'nloc Reisoued Apr. 26, 1927.

. UNITED STATES am! 1'. Lownns-rnm m nnwnnn a.

PATENT OFFICE.

CLEMENT, OF WASHINGTON, DISTBICTOI' GOLUIBIA, ASSIGNOBS, BY .IDIBECT AND ME SNE -ASSIGNMEN'I'B,\TO EDWARD F. COLLAIDAY,.OF WASHINGTON, DISTRICT OF- COLUMBIA. Y

name nncnrvnve nrr'sns'rus.

Original application filed August 14, 1922 Serial No. 581,778. Renewed July 22, 1924. Original No.

1,582,308, dated January 8, 1925. Application for Our invention relates to combined radiohone and telephone systems, and has for its object the provision of improved means by which an operator at a radio sw1tchboard 5 may supervise the operation of a radio receiving a paratus at a subscribers station. It has 11 proposed in such systems to provide a test or listening relay at the sub. scribers station, connected to the telephone wire circuit and controlled by a radio operator at central to connect the substation radio receiving apparatusor circuits to the wire circuit for telephonic transmission thereover to central, whereby the said radio operator may listen to the actual so'undsreceived and reproduced at the substation while broadcasting, with a view to the regulation and adjustment of the transmittlng instrument or the receiving instrument, or both. In the present case, we provide for such supervision by connecting a telephone transmitter to the contacts of the listening relay, and so relating said transmitter to .the 'receiver'or loud speaker of the radio receiving set' that air conduction of sound waves takes lace between them, and a test of the comp ete performance of the apparatus as a whole is ssible.

o Ourinvention is lustrated in the accom- .,a0 anying' drawing, in which the fi re isa iagram' showin a central oflice aving a telephone switch card and a" radio switchboard, a subscribers station equippedwith a telephone and a radio receiving set, and :5 the line circuit therefrom to central.

Referring to the drawing, 0 is thecentral oflice which for convenience; is shown -equip d with manual apparatus,but which may ave automatic switching apparatus, for the interconnection of telephone lines, or for the radio station control, or both.

The line 16-17 is connected as usual to terminals on the; telephone switchboard and to one or more multiple terminals on the radio switchboard, where the radio operator has cord circuits typified at Paaequipped with a switch Km for connecting battery to, the tip side of line, the cut of! relay of the line beat the same time energized to clear said so Life of ground at the central oflice, which is plates.

reissue filed January 8, 1927. .Serial No. 159,461.

normally connected through the windings of the line relay.

At the substation A, the telephoneT is a standard common battery instrument set. The radio receivin apparatus is equipped with another telep one set, comprisin transmitter T, receiver t, induction col -I,

hook switch H and condensers 9 ,3: I e radio set in itself forms no part of t e present invention, but'to supply-a loud speakmg horn for our urposes, is shownashav ing a detector tu 30, and two'stages'of audio amplification by tubes Hand 32. The usual transformers 33, 34 35 are provided with batteries A and B, for filaments and receive sound waves ,from the horn. When the hook H" is up it. closes the filament cir-- cuits as follows: A}, 25, 42,, H, 41', filaments, battery. When the hook is down, the radio operator at central can close the filament circuit and also thecircuit of transmitter T by pulling up relay L.

For this purpose, key Km is closed, and battery current flows over tip side 16 of line to the substation, thence through back contact of cult I, and back to battery, shown as by ground return, but may be by wire; line transmission circuit: 16 contact of L, 26, 27, 89, g, t, I, g, 40, 2 7, back contact of L, and so to sleeve side 17 of line. The operator thus controls both'the filament circuit and the repeat back circuit, and as the telephonic connection'between the line and the radio set includes the horn 36, a complete test is available of the entire ap arat us and the actual tones produced there y.

While we have described and shall claim herein combined radio hone and telephone systems specifically we 0 not limit ourselves ereby to any particular medium for broadcast transmission, the main featureof the invention being the centralized supervision of high frequency broadcastv reception over The horn 36 and the switch hook H are so related that when the telephone T is hung on thehook it will be in position to the wire circuit to central.

cast and telephone system, a centr a subscr bers station, a wire circuit mg them, a high .freipliency wave-receiving-v ii any suitable transmitting medium, by means of the actual air waves or sound waves issuing from the receiver at a receiving station.

Weclaim i 1-. In a combined radio and. telephone system, a central station, a subscriberssta-. tion, a wire circuit connecting them, a radio receiving set' at the subscribers station, and a telephone transmitter related thereto so as to receive sound waves therefrom with means controllable by a radio operator at the .central station to close the circuits of said transmitter for current supply thereto and for telephonic transmission over the wire circuit .to central.

.2. In a combined high frequenc broadstation, connect-- and-detecting set ate subscribers-station" and a telephone transmitter related theretoso as to receive sound waves therefrom, with means at the central station to close the circuits of said transmitter for current supply v theretoand for telephone transmission over 3. In a high frequency'broadcastsystem,

a plurality of receivin stations having re- Y ceivi wave ength, a common transmitting station apparatus tune to a fixed standard equipped with transmitting up} aratus tuned to said standard wave lengt apparatus for determining when the receivmg apparatus at a receiving station is operating in resonance with the broadcast transmitter, comprising a wire circuit extending from said supervisory apparatus to said receiving station, and a telephone transmitter connected to said wire circuit 'at the receiving station and related to the broadcast resupervisory 4. In a high frequency broadcast system,

a'plurality of receiving stations, a high frequency Wave-recei-ving-and-detectingv set at I each station and a telephone transmitter related thereto so as to receive sound" waves therefrom, and a central supervisory station having awired circuit connection to said telephone transmitter. 1 5.-'In a high frequency broadcast system, a plurality of receiving station's, a high frequency wave-receiving-and-detectin set at each station and a telephone transmitter related thereto so as to receive sound waves therefrom, and a central supervisory station having a wired circuit connection to said telephone-transmitter, together with means at said supervisory stationto close the circuit of said transmitter for telephonic transmission over said wire circuit-to the superviso station. a i I 6. e method of supervising and regu- "latin high frequency broadcast distribution whic consists in transmittingovera suitable medium and receivingtherefrom at a plurality of tuned receivin stations, causing the apparatus at each stationto 'r' roduce the ori 'nal audio modulations int e form of au i ble air waves or sound waves, causing said sound waves to be transmitted tele-fphonically to and received eta common point;

In testimony our signatures.

' HARRY FL LOWENSTEIN. EDWARD E. CLEMENT,

whereof we 

